                                (dissoc-in [:chs ch :msgs msg])))
                (when (nil? msg) ; The ch is closed.
                  (swap! vis #(dissoc-in % [:chs ch])))
-               [{:delta :take :msg msg :ch ch :actx actx :phase :prev}]))}
+               [{:delta :take :msg msg :ch ch :actx actx :phase :prev :ch-name ch-name}]))}
    :aput
    {:before (fn [vis actx args]
               (let [[ch-name ch msg] args]

                                (assoc-in [:actxs actx :wait-chs ch] [:put ch-name])
                                (vis-add-ch ch nil)
                                (assoc-in [:chs ch :msgs msg] true)))
                [{:delta :put :msg msg :actx actx :ch ch :phase :prev}]))
    :after (fn [vis actx args]
             (let [[ch-name ch msg result] args]
               (swap! vis #(-> %

                         "<line class='delta' x1='0' y1='0' x2='100' y2='"
                         (- (ch-y (:ch delta)) (actx-y (:actx delta)))
                         "' stroke='green' stroke-width='1' marker-end='url(#triangle)'/>"
                         "</g>"
                         (when (:ch-name delta)
                           ["<text class='ch-name' x='540' y='"
                            (* 0.5 (+ (actx-y (:actx delta)) (ch-y (:ch delta))))
                            "'>" (:ch-name delta) "</text>"])])
                 :take (when (get chs (:ch delta))
                         ["<g transform='translate(600," (ch-y (:ch delta)) ")'>"
                          "<line class='delta' x1='0' y1='0' x2='-100' y2='"
                          (- (actx-y (:actx delta)) (ch-y (:ch delta)))
                          "' stroke='" (if (:msg delta) "green" "black")
                          "' stroke-width='1' marker-end='url(#triangle)'/>"
                          "</g>"
                          (when (:ch-name delta)
                            ["<text class='ch-name' x='540' y='"
                             (* 0.5 (+ (actx-y (:actx delta)) (ch-y (:ch delta))))
                             "'>" (:ch-name delta) "</text>"])])
                 :actx-start (when (> (actx-y (:child-actx delta)) line-height)
                               ["<g transform='translate(30," (actx-y (:actx delta)) ")'>"
                                "<line class='delta' x1='0' y1='0' x2='30' y2='"
